1. Field of the Invention
The present invention relates to a digital signature method using a public key cryptogram, and an information communication system and apparatus using such a method.
2. Related Background Art
With developments and wide spreads of computers and communication networks, various functions such as social activities heretofore impossible on communication networks can be realized.
In some cases, however, it is easy for a third party to know a person, time, place, and contents during communications.
In order to prevent this, methods have been proposed which perform anonymous communications to protect privacy and realize various functions on communication networks.
For example, there is a method using a public key cryptogram. With this method, a sender can transmit communication contents only to a receiver the sender wishes to communicate, and the receiver can reliably confirm who is the sender of the received communication contents.
This method is applied to the digital signature method and an information communication system using this method disclosed in Japanese Patent Application Laid-open No. 9-108225.
"Cryptograph" and "Anonymous public key certificate" will be specifically described.